A new way to sniff out health problems

Whether it’s the aroma of the salty ocean, freshly cut grass, or a pie baking in the oven, smells have the power to improve our mood, trigger memories, and even alert us to potential danger. In fact, our sense of smell is so vital that its loss can be a strong clue that something has gone wrong in the body.

An invention from Johns Hopkins biomedical engineering students could help clinicians detect and treat smell dysfunction earlier. Called ScentCare, the system comprises two components: a cylinder case containing scented inhaler cartridges, and a companion smartphone app that guides users through smell testing and retraining exercises. This straightforward approach requires no expensive equipment or fine motor movements– just a simple sniffing device and a smartphone – making it potentially more accessible than other smell tests, especially for older adults.

“We focused on building something simple that does both testing and retraining with just one device, because there is no device that does both on the market yet,” said ScentCare team member Mili Ramani, a fourth-year biomedical engineering major. “The novelty is that this is much less cluttered and more standardized.”

Ramani and Angela Sadlowski, also a fourth-year biomedical engineering major, started working on the project as first-years in the Department of Biomedical Engineering’s Design Team Health-Tech Project course, where undergraduates learn to use engineering principles to solve design problems related to human health.

Smell (called olfaction) is usually assessed with a scratch-and-sniff test called the University of Pennsylvania Smell Identification Test (UPSIT). But because UPSIT isn’t part of routine health screenings, many people don’t even realize their sense of smell is lacking or otherwise altered.

“Before joining this project, smell wasn’t something I thought much about, it’s just something that I had,” said Ramani. “It’s an overlooked sense, and part of this project is spreading awareness about the importance of testing your sense of smell.”

Testing using ScentCare system is simple: Sniff each inhaler cartridge and choose the correct scent via a multiple-choice test on the app. The cartridges represent one of the four main scent families: woody/earthy, floral, citrus, and herbal/spicy.

The user’s final score can tell clinicians if there is cause for concern; smell loss is an early sign of viral infections like COVID-19, neurodegenerative diseases, brain injuries, and even depression. For example, the inventors suggest that ScentCare device could be used to test people at a high risk of Alzheimer’s disease, leading to earlier diagnosis.

Though loss of smell can indicate health issues, in many cases, people can regain their sense of smell through a technique called “smell training.” Roughly 40% of patients improve significantly after undergoing that process, which the ScentCare system makes simple.

“Using the inhaler cartridges and app, patients sniff the lemon scent while looking at a photo of a lemon for at least 15 seconds, once or twice a day,” said Sadlowski. “How does this work? It’s an example of what we call ‘neuroplasticity,’ or the ability of neurons to rebuild connections between the olfactory system and the brain.”

Regaining a sense of smell isn’t just important to a patient’s quality of life; it’s also a safety issue. Not being able to smell fire or gas can be very dangerous, which is why the team included campfire as one of their training scents, adds Sadlowski.

The inventors’ ultimate goal is to get the technology into clinics to make smell testing more common, and into homes of people who can benefit from retraining. To this end, they have applied for patents and are currently recruiting participants for a clinical trial using the gadget with older adults, a cohort they selected because aging is a major cause of smell loss.

Sadlowski and Ramani, who are both heading to medical school next fall after graduation, are deeply gratified that something they’ve been working on since their first year at Hopkins – and started out designing with Play-Doh and popsicle sticks – is now an actual device.

“The original course was about building skills and just coming up with a proof-of-concept. But this project ended up becoming translational and we started working with clinicians and on the business side,” said Sadlowski. “It’s been exciting to see how far it’s gone beyond the course and is closer to being in the real world. That’s more than I could have asked for.”

The students are mentored by Constanza Miranda, an associate teaching professor in the Department of Biomedical Engineering, and Nicholas Rowan, an associate professor of in the Department of Otolaryngology-Head and Neck Surgery. Along with Sadlowski and Ramani, the ScentCare team currently includes fourth-year computer science student Elaine Zhao and third-year mechanical engineering student Eva Loftus.